IEEE 802.11 is a set of media access control (MAC) and physical layer (PHY) specification for implementing wireless local area network (WLAN) communication in the Wi-Fi (2.4, 3.6, 5, and 60 GHz) frequency bands. The 802.11 family consists of a series of half-duplex over-the-air modulation techniques that use the same basic protocol. The standards and amendments provide the basis for wireless network products using the Wi-Fi frequency bands. Recently, WLAN has seen exponential growth across organizations in many industries.
Orthogonal frequency division multiple access (OFDMA) technology has developed in the cellular networks enabling multiple users to share the same wideband frequency range at the same time. Such technology, however, has not been developed for WLAN networks. How to adapt the OFDMA technology to WLAN networks so to enable sharing of the same wideband frequency range among multiple users remains a question. For a normal uplink OFDMA operation, an access point (AP) needs to collect the traffic requests from wireless devices (STAs), arranging and managing the resource used by STAs for the uplink OFDMA transmission. However, only using designated resource for uplink OFDMA may not be efficient.
In OFDM/OFDMA wireless systems, contention-based uplink transmission is commonly used for multiple user equipments (UEs) to transmit uplink data to a serving base station via a shared uplink channel. For example, a UE may request access and acquire ownership of an uplink channel to initiate transmission. Therefore, in WLAN, contention-based random access can also be used for uplink OFDMA operation. For contention-based random access, multiple STAs contend for shared resource.
To improve the efficiency of the WLAN network allowing multiple users to share the same wideband WLAN channel, improvement and enhancement are required for the WLAN network.